A forum "troll" is someone who is tossing out an outrageous opinion with the hope of igniting a controvertial or heated discussion. Sort of like "trolling" bait behind a boat in hopes of catching a fish. Quite often a troll doesn't even believe what they are stating, just enjoys the flame war that follows. The best way to respond is to not respond- "do not feed the trolls".

"Nuke the unborn gay whales for jesus"- now that's a troll.